摘要:

The diode bias dependence and the spectral response of the external emission of photo‐induced conduction electrons have been investigated experimentally and analytically for reverse‐biased surface‐barrier diodes. An anisotropy has been observed in the diode bias dependence. Variation of the mean‐free path of hot electrons with impurity densities in silicon is suggested by comparing the experimental result with the analytical one.

ISSN:0021-8979    

DOI:10.1063/1.1659147

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The energy distribution of electrons emitted from surface‐barrier diodes made ofp‐type silicon with aluminum contacts has been investigated in an attempt to clarify the behavior of electrons in a high electric field in silicon. Free electrons have been produced in thep‐type silicon by irradiated light and accelerated in the depletion layer of a reverse‐biased diode to escape into vacuum from the cesium‐treated surface of the thin aluminum contact. Energy distributions of the emitted electrons have been measured under various conditions using the retarding field method. The energy distributions of the electrons in the silicon have been obtained from those of the emitted electrons. They cover the energy region from 1.5 to 4 eV above the conduction‐band bottom of silicon. Different energy distributions have been found for [111] and [100] directions of the accelerating electric field. By using Keldysh's theory with known parameters, the mean‐free paths of hot electrons between phonon scattering have been determined to be 45 and 52 Å by fitting the experimental energy distributions to the calculated ones for acceleration of electrons in the [111] direction and for acceleration of electrons in valleys of easy acceleration in the [100] direction respectively.

ISSN:0021-8979    

DOI:10.1063/1.1659148

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The photometric method has been proven successful in the measurement of the ionization frequencyviin dry air in the field range 40≤Eeff/p≤132 V/cm Torr. The ionizing agent was a 9.361‐GHz rectangular pulse which traversed a fused quartz breakdown cell enclosed in a cylindrical waveguide. As in previous studies, the electron collision frequency was selected according to the valuevc=5.3p×109sec−1. The pressures chosen ranged from 0.5 to 36 Torr. The measurements were confined to the last half portion of the formative time lag (FTL) interval but always before manifestation of breakdown occurred as seen by abrupt changes in reflection and transmission signal pulses. Thevi/pversusEeff/pcurve thus found ran reasonably parallel to the curve obtained by other workers who used the FTL‐method. Compared to their results, however, the present curve was shifted towards highervi/pvalues by as much as a factor of 1.8 in the lower one‐half portion of theEeff/p‐range.

ISSN:0021-8979    

DOI:10.1063/1.1659149

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The problem of a charged axially symmetric body inside a cylindrical tube is studied by using the method of matched asymptotic expansions. The shape of the body is assumed arbitrary. It is found that when the body dimensionais small compared with the tube radiusRa simple approximate formula for the capacitance of the system is given byC=Co [1−(&ggr;Co /4&pgr;&egr;0R)]−1+0(a2/R2),whereCois the capacitance of the isolated charged body, and &ggr; is a universal constant, independent of the body shape, and approximately equal to 0.87.

ISSN:0021-8979    

DOI:10.1063/1.1659150

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The system of coupled equations which governs the electric field, ion densities, and aerosol charge in a quiescent cloud between semi‐infinite charged plates is solved numerically for the case when ionization is confined to a layer near each plate and the case of volume ionization. The results predicted by the governing equations are verified experimentally. The electrical stress produced in the case of volume ionization tends to stabilize the fluid whereas surface ionization can produce hydrodynamic instability. The electroconvective instability produced by surface ionization is easily observable both visually and electrically. If turbulence is generated in the chamber by mechanical means, the turbulent transfer of charge will oppose the conduction current in the case of volume ionization and enhance the total current in the case of surface ionization.

ISSN:0021-8979    

DOI:10.1063/1.1659151

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

An iterative numerical technique has been employed to model the decay of plasmas in an electronegative gas, nitric oxide, and in an electropositive gas, helium. The spatial and temporal behavior of the charged species are followed and compared with experiments through four regimes: (1) positive ion‐electron ambipolar diffusion regime, (2) transition regime, (3) positive ion‐negative ion ambipolar diffusion regime for an electronegative gas, and (4) free diffusion regime for an electropositive gas. Densities of all charged‐particle species are calculated from Gauss' law. The structural features in the experimental measurements of decaying plasmas are reproduced in the results of the numerical calculation.

ISSN:0021-8979    

DOI:10.1063/1.1659152

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Large‐current‐produced noise was observed in polycrystalline iodine samples in a range where the conduction is Ohmic. The voltage and frequency dependence between 5 and 500 Hz wasV3/f2. At lower frequencies the spectrum seemed to approach a variation asV2and to become independent of frequency indicating relaxation times of 200–600 msec. Large spatial correlations were observed with a lag time indicating positive charge carriers with a mobility about 1.3 cm2/V sec. These measurements are consistent with conduction taking place by the motion of clusters of charges where a cluster moves distances of the order of millimeters with a mobility of the order of 1 cm2/V sec. Difficulties with the sample reproducibility precludes more detailed analysis but the results indicate that noise measurements may be a useful method to study the mechanism of electrical conduction in low‐mobility materials.

ISSN:0021-8979    

DOI:10.1063/1.1659153

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The noise spectrum due to fluctuations of electron‐hole pairs in a semiconductor in the presence of uniform and time‐independent electric and magnetic fields is presented in this paper. This spectrum is obtained via the Green's function for the macroscopic differential equation which governs the behavior of the conditional average for fluctuations in the electron‐hole pair particle density when generation‐recombination and ambipolar drift are the only important processes. For the general situation when the electric and magnetic fields are not collinear, the obtained spectrum is a complicated function of both frequency and magnetic field for a fixed value of electric field. From this spectrum the spectra corresponding to the special cases when the electric field is parallel and perpendicular to the magnetic field are obtained. Since the case when the electric field is perpendicular to the magnetic field is the most interesting from an experimental viewpoint, it is discussed in more detail and illustrative plots of the spectrum are presented.

ISSN:0021-8979    

DOI:10.1063/1.1659154

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The bolometer depends on the rapid temperature variation of the current in an avalanching semiconductor. Typically, at 1.7°K, it has a sensitivity of 0.05 V W−1, a response time of 2×10−7sec, and a noise equivalent power of 10−7W Hz−1/2. The rapid response is possible because only a thin damaged layer at the surface of the semiconductor is involved in the detection process. We have used the device to detect heat pulses in magnetic fields up to 30 kOe.

ISSN:0021-8979    

DOI:10.1063/1.1659155

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The thermally stimulated current (TSC) technique has been used to study the release of charge injected into Mylar films with both short (&mgr; sec) and long (10 sec) voltage pulses. The electric field applied across the Mylar is as high as 800 kV cm−1. The TSC spectrum is complex with the peaks at low temperature depending on the type of electrode used and the sign of the voltage pulse. A current reversal exists, which leads to peaks of both signs indicating the possibility that double‐injection has occurred. The spectrum at low temperature is characterized by 1/fnoise arising possibly from ``slow'' surface states. At high temperatures (410°–450°K) a peak from a deep trapping level occurs with a trap energy estimated to be 1.6–2.0 eV. The spectrum is discussed in terms of possible trap mechanisms.

ISSN:0021-8979    

DOI:10.1063/1.1659156

出版商:AIP    

年代:1970

数据来源: AIP